X-ray, Optical & Infrared Images of M101
The galaxy Messier 101 is a swirling spiral of stars, gas, and dust. Messier 101 is nearly
twice as wide as our Milky Way Galaxy. Spitzer's view [bottom right frame], taken in infrared light, reveals the galaxy's delicate dust lanes as yellow-green filaments. Such dense dust clouds are where new stars can form. In this
image, dust warmed by the light of hot, young stars glows red. The rest of the galaxy's
hundreds of billions of stars are less prominent and form a blue haze. Astronomers can
use infrared light to examine the dust clouds where stars are born.
Messier 101 has a pancake-like shape that we view face-on. This perspective shows off
the spiral structure that gives it the nickname the Pinwheel Galaxy. In this Hubble image
[middle right frame], taken in visible light, the bright blue clumps are regions where new stars
have formed. The yellowish core consists mainly of old stars. The dark brown dust lanes
are colder and denser regions where interstellar clouds may collapse to form new stars.
All of these features are shaped into a beautiful spiral pattern by a combination of gravity
and rotation. Astronomers use visible light to study where and how stars form in spiral
galaxies.
Chandra's image of Messier 101 [top right frame], taken in X-ray light, shows the high-
energy features of this spiral galaxy. X-rays are generally created in violent and/or high-
temperature events. The white dots are X-ray sources that include the remains of
exploded stars as well as material colliding at extreme speeds around black holes. The
pink and blue colors are emission from million-degree gas and from clusters of massive
stars. The pink emission indicates lower-energy X-rays and the blue higher-energy X-
rays. One reason astronomers study Messier 101's X-rays is to better understand how
black holes grow in spiral galaxies.
(Credit: X-ray: NASA/CXC/JHU/K.Kuntz et al.; Optical: NASA/ESA/STScI/JHU/K. Kuntz et al; IR: NASA/JPL-Caltech/STScI/K. Gordon)